In a dye diffusion transfer recording system (hereinafter also referred to as a sublimation transfer recording system), a heat-sensitive transfer sheet (hereinafter simply also referred to as an ink sheet) containing a colorant (hereinafter also referred to as a dye) is superposed on a heat-sensitive transfer image-receiving sheet (hereinafter simply also referred to as an image-receiving sheet), and then the heat-sensitive transfer sheet is heated by a thermal head whose exothermic action is controlled by electric signals, in order to transfer the dyes contained in the heat-sensitive transfer sheet to the image-receiving sheet, thereby recording an image information. Three colors: cyan, magenta, and yellow, or four colors which consist of the three colors and black are used for recording a color image by overlapping one color to other, thereby enabling transferring and recording a color image having continuous gradation for color densities.
On the other hand, in recent years, demands on color images are diversified, and there is a demand for obtaining three-dimensional images conveniently and inexpensively. It has been known that, so as to make a picture, a photograph, or the like appear stereoscopic, a lenticular lens (sheet-shaped, hereinafter also referred to as a lenticular lens sheet) formed from semi-cylindrical lenses is attached on a printed picture or photograph correspondingly to the right-side eye and the left-side eye. Along with the popularization of three-dimensional images, the three-dimensional images are required to be a stereoscopic image with accuracy, and to be a high grade image, free from an image defect, unevenness, and the like, like color images of other systems.
Japanese Patent No. 3609065 discloses an image recording apparatus equipped with a recording unit that records an image on the back side of the lenticular lens sheet, a moving mechanism for moving the recording unit and the lenticular lens sheet relatively to each other, a position detecting unit provided to be contacted with the concave parts and/or convex parts of the lenticular lens sheet, and a recording control unit that controls the recording unit to perform recording while detecting the position of the lenticular lens sheet by means of the position detecting unit.
Japanese Patent No. 3789033 and JP-A-9-300828 (“JP-A” means unexamined published Japanese patent application) discloses a method of producing a lenticular lens sheet printed material, including: preparing a heat transfer sheet provided with a coloring material transfer unit and a white layer transfer unit in area order on the same surface of a substrate film; thermally moving the coloring material from the coloring material transfer unit to the back surface of the lenticular lens sheet by using a heating device; and subsequently thermally transferring the white layer.
JP-A-6-282019 discloses a heat-sensitive transfer recording sheet for stereoscopic photographs, which utilizes the lenticular lens sheet as a substrate and has a dye receptor layer provided on the back side of the lenticular lens sheet.
JP-A-2008-246949 discloses that, in drying in a production of the heat-sensitive transfer sheet, a film surface temperature is kept in a range from 5° C. to 20° C. until drying of 60% of total water content is completed.
However, there is posed a new problem that when images are printed using such the lenticular lens sheet and the heat-sensitive transfer image-receiving sheet, a transfer failure in the form of black or colored spots occurs in middle or high-density image areas. This problem is prone to occur when the images are printed under high temperature and high humidity conditions, and thus it is strongly demanded to solve this problem.